Air conditioning system



April 15, 1941- G. D. GULER 2,238,688

AIR CONDITIONING SYSTEM Filed June 16, 1938 2 Sheets-Sheet 1 ,41 ilb 53 5 ill dieorgeDofiulen (Ittomeg Ap 15,1941. G. D. GULER AIR CONDITIONING SYSTEM 2 Sheets-Sheet 2 Filed June 16, 1938 1 w w r 1/l \M w r W% fi o flm m a O I q W. w M w w 4 Q x a l W N m a W. 5 f w 5 m K j a 1 .l w a a 3 r H Q 2 m m 1 2 w w m m u 2%, IF 0 U2- I I ma MS m Patented Apr. 15, 1941 umrsn STATES PATENT OFFICE- 2.23am I 5 Am connrrromo srs'rnm (its... 1). Guler, Philadelphia, 1a.. trainer to Minneapolis-Honeywell Minneapolis,

Company.

Minn, a eorporation'of'belaware Application Ju e 18,1938, Serial No. 214,033

(Cl. zs'r-s) llclaiinl.

This invention relates toan air conditioning system and more particularly to an air conditioning system wherein a plurality of zones are conditioned by a single air conditioning apparatus, the system being so arranged that the same apparatus may be utilized for cooling one zone when a difierent zone is calling for heating.

It is an object ofthis invention therefore to provide an air conditioning-system having both heatingandcooling means, the system being so arranged that the conditions of a plurality of zones are individually controlled by the same system and wherein onezone may be cooled by the system while another zone may be heated if conditions so require.

Another'object of the invention is the provision of an air conditioning chamber divided into means for operating both the heating and cooling means when the mixture temperature is between these values, and means for proportioning the amount of air passing through the sub-chambers into each space according to the requirements of the space.

Incarrying out my invention I provide an air conditioning chamber divided into a pair of subchambers, one of the sub-chambers having heating means, and the other of the sub-chambers having cooling means therein. Each of the subtemperature of the air being delivered thereto, the conditions in each zone may be effectively controlled.

'Other objects and advantages may become apparent upon a study of the specification, claims, and appended drawings wherein like reference characters represent like parts in the two views and wherein:

Figure 1 is a schematic diagram of my air conditioning system. and Figure 2 is a schematic diagram illustrating the manner in which the conditionedair is delivered to the various zones to be conditioned- Referring now to the drawings, an air conditioning chamber is represented by the reference character III. This chamber is divided into a pair of sub-chambers and2l bymeansof awall II and as will be seen with'reference to Figure 2 the various sub-chambers are divided adjacent the outlet portions thereof into separate eways by walls l2, I2. Ducts I2 provide communication between the various eways and the spaces H to be conditioned. While only three such passageways and spaces have been illustrated in the drawings, it will be understood that the chamber l0 may be divided into as many passageways as is necessary for the particular ins'tallation. Dampers l1 and I2 in the chambers 20 and 2|, respectively, are connected. to an actuating rod I! which is operated ina manner to be hereinafter set forth. The dampers are so arranged that as the dampers "controlling the sub-chamber 20 are moved to closed position, the dampers It in the sub-chamber 2| will. move towards open position and vice versa. Each of the passageways are controlled by similar dampers as illustrated in Figure 2, only the dampers l'l being illustratedin this figure.

- Air is circulated through the chambers 24 and 2|, the ducts i2 and the spaces M by means of a fan 23 driven by a motor 24. return air are delivered to the-fan 22, the fresh air entering through an inlet 25 and return air entering through an inlet 26. Dampers 21 and 22* control the proportions of fresh and return air that are delivered to the fan 22, these dampers being operated in a manner to be described. A reliefoutlet 29 is provided through which the air from the conditioned spaces may pass when fresh air is admitted to the system and this outlet is controlled by suitable dampers 34. A wall 32 divides the fresh air inlet into separate passageways, one of these passageways being controlled by the dampers 21 and the other passageway being controlled by a manually addustable damper 34. When the dampers 2! are in fully closed position, a minimum amount of fresh air will be admitted to the system through the passageway controlled by the damper 34, the amount of such air being dependent upon the settingof this I damper.

Mounted in the sub-chamber 24 are a pair of heating coils 36 and 31 through which steam or any suitable heating medium flows under the control of valves 38 and 29, respectively. In the subchamber 2| are four sets of cooling coils 44, 4|, 42,

and 42 through which a suitable cooling medium flows under the control of the valves 44, 45, 46, and. 41, respectively. The operation of the valves controlling the heating and cooling. coils will be described in detail subsequently.

Both fresh and A motor 50 is provided for controlling the position of the fresh air dampers 21, an arm 5| driven by this motor being connected by means of a link 52 to the damper operating arm 53. This motor may be a proportioning motor of the type illustrated in Patent 2,028,110 issued to D. G. Taylor January 14, 1936. The operation of this motor is controlled bya temperature responsive device 54. This device may include a bellows 55 connected by means of a capillary tube 56 to a bulb 51 located on the dischargeside oi! the fan 23. This tube, bulb, and bellows may be filled with a suitable volatile fluid which expands and contracts in accordance with variations in temperature of the air passing over the bulb 51. As the temperature of the air passing over the bulb fails, the bellows contracts and upon a rise in temperature the bellows 55 will be expanded. A lever ,58 has an arm 59 biased by means of a spring 60 into engagement with the upper portion of the bellows 55, the other arm SI of this lever being arranged to move over a resistance 52. As the bellows 55 contracts in response to a fall in temperature of the air leaving the fan 23, lever 6| will move toward the left over the resistance 62 under the influence of the spring 50 and upon a rise in temperature the bellows will cause movement'of the lever 6| in the opposite direction. A second temperature responsive device 65 is also provided for controlling the operation, of the motor 50. This temperature responsive device includes a bellows I56 connected by means of a capillary tube 61 with a bulbB8 located in the path of fresh air entering the fan 23. This tube, bulb, and bellows are provided with a suitable volatile fluid and biased by means of a spring 10 into engagement with the top of the bellows 66 is a lever 1| pivoted at 12 and carrying a mercury switch 13 having contacts 14, 15, 16, and 11. When the temperature of the air entering the fresh air inlet is below a predetermined value such as 75 F.. the mercury switch 13 will be tilted in the direction illustrated whereby the contacts 14 and 15 are connected by the mercury element 18. Upon a rise in temperature of the fresh air above this value the switch 13 will be tilted in the opposite direction whereupon the contacts 16 and 11 will be connected by the mercury element 18; With the switch in the position illustrated the arm 6| of the temperature responsive device 54 is connected to the center terminal 19 of the motor by means of conductors 80, contacts 14 and 15 of the mercury switch 13 and conductor 8|. Conductors 82 and 83 connect the extremities of resistance 62 with terminals 84 and 85 of the motor 50. Arm SI and resistance 62 form a control potentiometer for the motor 50 and it will be understood upon an examination of the above referred to Taylor patent that as the arm 6| moves with respect to resistance 62 in response to variations in temperature of the air leaving the fan 23, motor 50 will cause movement of the arm 5| an amount which is proportional to the change in the air temperature, and this in turn will cause a proportionate movement of the dampers 21. As the temperature of the air decreases, the arm 6| moves to the left over resistance 62. The external resistanceacross the terminals 19 and 84 of the motor 50 will decrease causing movement of the arm 5| to the right and closing movement of the dampers 21. Upon' an increase'in the air temperature arm 6| will move toward the right thus decreasing the resistance across the terminals 19 and 85 moving arm 5| toward the left and the dampers 21 toward open position. Thus, upon a rise in the temperature of the air leaving the fan, the dampers move toward open position, and upon a drop in temperature the dampers move towards closed position, the controller 54 maintaining the temperature at about 58 as long as the outdoor temperature does not rise too high. When the temperature of the fresh air rises above 75, however, the mercury switch 13 is tilted in the opposite direction and contacts 16 and 11 are connected together; The result of this is that there is no external resistance between the terminals 19 and 84, these terminals being connected together as follows: from the terminal 84 throughconductor 90, contacts 11 and 16 of the switch 13 and conductor 8| to the terminal 19. The connection between terminal 19 and arm 6| of controller 54 is broken so that this controller now has no effect on the operation of motor 50. The motor 50 will now operate to move the dampers to their entirely closed position so that the only fresh air admitted to the fan 23 is that which passes by the damper 34.

Also operated by the motor 50 is an arm 92 which sweeps over a potentiometer resistance 93, this arm and resistance forming the control potentiometer for a motor 94 similar to the motor 50. The'arm 92 is connected by means of conductor 95 to the center terminal of the motor 94 and the extremities of the resistance 93 are connected by means of conductors 91 and 98 to the outer terminals of the motor 94. ,An arm I00 is driven by the motor 94 and is connected by means of a link II to the dampers 28. The arrangement is such that as the dampers 21 are moved towards open position, for example, potentiometer 92 causes motor 94 to operate to move the dampers 28 towards closed position and as the dampers 21 are moved towards closed position damper 28 will move towards open position. The movement of the dampers is such that the same amount of air will be admitted to the fan 23 regardless of the proportions of fresh and return air as controlled by the dampers 21 and 28. Motor 94 also causes operation of an arm I04 over -a potentiometer resistance I05, this arm and potentiometer forming the control potentiometer of a proportioning motor I06, this mo- I tor including an arm I01 connected by means of a link I08 to the dampers 39. The arm I04 is connected by means of a conductor IIO to the center terminal of the motor I06 and the outer terminals of the motor are connected by means of conductors H2 and H3 to the extremities of resistance I05. The arrangement is such that as the dampers 28 move towards closed position the dampers 30 will move toward open position, or

, in other words, as the dampers 21 move towards open position allowing additional fresh air to the system the dampers 30 will also move towards open position thus allowing some of the return air to be exhausted from the system so that the total volume of air throughout the system will at all times remain the same.

It will now be seen that the quantities of fresh and return air are varied in accordance with the temperature of the mixed air being discharged from the fan 23 and upon a decrease in this air temperature the amount of fresh air is decreased and the amount of return air is correspondingly increased. The temperature of the air leaving the fan will be maintained at approximately 58 except when the fresh air temperature rises so high that the opening of dampers 21 is ineffective line I8I.

in keeping this temperature at this value. when the temperature of the fresh air reaches 75 the fresh air dampers 21 are entirely closed and dampers 28 will be entirely open, the only fresh -air now being admitted to the system being by provided with a suitable volatile fluid so that the bellows I2I will expand or contract as the temperature of. the air leaving the sub-chamber 2| varies. An arm I28 of a bellcrank lever I28 is biased by means of a spring I28 into engagement with the top. of the bellows I2I, and the other arm I21 of this lever is arranged to sweep across a potentiometer resistance m. It will now be apparent'that as the temperature of the air leaving the chamber 2I rises, bellows I2I will expand and cause movement. of arm I21 toward the right over resistance I28. The arm I21 is connected by means of a conductor I38 with the center .termie nal oi a proportioning motor I32 similar to the motor 58. The outer terminals of this motor are I connected by means of conductors I33 and I38- will be maintained at a substantially uniform value which may be, for example, 58''. The operation of the valve 38 which controls the supply of heating medium to the heating coil 38 located in the heating chamber'28 may be controlled by a proportioning motor I similar to the motor 58. The motor I15 is controlled primarily by a temperature responsive device I18 comprising a bellows I11 connected by means of a capillary tube I18 to a bulb I18, this tube, bulb and bellows being filled with a suitable volatile fluid and the bulb I18 being located at the discharge side of the heating chamber 28. -A spring I82 biases the arm I83 of a lever I88 into engagement with the upper portion of the bellows I11 and the other arm I85. of the lever is'arranged to move over a potentiometer resistance I88 in response to changes in temperature of the air leaving the chamber 28. The right end of resistance I88 is connected by means'of conductors I88 and I8I with the lower terminal of the motor I15. The opposite end of the resistance I88. is connected by means of conductors I82 and I83 with I85 is connected to. the center terminal of the motor I15 by means of a center tapped resistance with the opposite ends of resistance I28. A shaft I38 driven by the motor I32 carries cams I38, I38, I88, and I. These cams operate switch arms I83, I88, I88, and I88, respectively, these'switch I arms cooperating with fixed contacts I81, I88, I88, and I58, respectively. Asthe temperature of the air leaving the chamber 2| rises and arm I21 moves toward the right over resistance I28, motor l32 will cause rotation of shaft I38 an amount proportional to this rise in temperature I88 over which the arm I85 moves conductors I81 and I88. As the temperature of the air leaving the chamber 28 falls, arm I85 moves toward the left-over resistance I88, the resistance connected between the upper and center terminals of the motor decreases and motor I15 is operated to open the valve 38, the motor being connected with the valve by means of arm 288 driven thereby and link 28I connecting the arm to the valve.

The control eflect of the temperature responsive device I18 is varied in accordance with and. switch arms I83, I88, I85, and I88 will be successively moved into engagement with their 'tact I81 thus energizing the solenoid I52 as follows: from the line I88 through conductors I85, I88, switch arm I83, contact I81, conductor I81, solenoid I52, and conductors I68 and I88-to the Energization of solenoid I52 causes the opening of valve 88 whereupon suitable refrigerant or other cooling fluid is admitted to the cooling coil 88. Should the temperature of the air leaving chamber 2| continue to rise, switch tube 281 to a bulb 288 located in the fresh'air inlet, this tube, bulb, and bellows being provided with a suitable volatile 1111. The arm 218 of a bell crank lever is biased into engagement with the bellows 288 by means of a spring 2I2, the other arm 2I3 of this lever being arranged tomove over a resistance 2 in response to .variations in temperature of the fresh air. The left arm I88 will be moved by cam I38 into engageinfluence of gravity or a suitable biasing means (not shown). It will thus be seen that the temperature of the air leaving the sub-chamber 2i end of the resistance 2 is connected by means fof conductors 2I8 and I83 to the upper terminal of the motor I15. The opposite end of resistance 2| 8 is connected by means of conductors 2I8 and I8I to the lower motor terminal and the arm 2I3 motor.. Both of these controllers act to cause 8 an opening of the valve 38 in response to a drop 'in temperature of the bulbs of these controllers,

but since the variable resistance In is interposed between the center terminal of the motor I15 and the arm 2I3 of controller 285, this controller will have less effect on the motor I15 for a given movement thereoi' than will the arm I85 of the controller I18; In other words, for a movement of arm 2I3 from one end of the resistance 2" to the opposite end the valve 38 may be moved from open to completely closed position whereas the same result may be accomplished by movement of arm I35 throughout the distance .x on the resistance I88. The result of this is that the control range X of the arm I85 will be shifted as the outdoor temperature varies. Thus upon a decrease in the fresh air temperature the control range of the arm I85 will be shifted towards the left so that a higher temperature of the air leaving the chamber 28 will result. By reason of the provision of the center tapped resistance I96 over which the control arm I85 travels the control range X will be of the same length regardless of the position of this control range with respect to resistance I88. The temperatures of the air leaving chamber28 will be, maintained between 80f F.

and 110 F. depending upon outdoor temperatures.

Operated by motor I is an arm 225 which travels over a resistance 226, this arm and resistance forming a control potentiometer for a proportioning motor 238 having its arm 23I operated thereby connected by means of a link 232 with the valve 39 controlling the flow to the heating coil 31. The opposite ends of this resistance are connected by means of conductors 235 and 236 to the outer terminals of the motor 238 and the arm 225 is connected by means of the conductor 221 to the center terminal of the motor 238. 'When the arm 225 starts to move on the resistance 226, the motor 238 will be operated to move the valve 39 towards open position. The valve 38 which controls the flow of heating fluid to the coil 36 is made over size so that when this valve is partially open, say, for example, half open, the heating coil 38 will be supplied with the maximum amount of heating .fluid it can handle. Further opening movement of this valve will not increase the amount of fluid which passes through the coil 36 but when this valve has been opened to a point where the coil 36 is operating at maximum capacity the arm 225 will start to move over the resistance 226 and if the temperature of the air leaving the chamber continues to fall below the desired value the operation of motor I15 will continue under the control of the controller I16 whereupon the motor 238 will start to open the valve 39 and admit heating fluid to the heating coil 31. It will thus be seen that with this arrangement the heating coils 36 and 31 will be operated in sequence if the heat added to the air by the coil 36 is not suflicient to maintain the desired temperature of the air leaving the heat--' ing chamber 20.

Also located inthe heating chamber is a spray device 248 for adding moisture to the air when the humidity of the air in the building being conditioned falls below a desired value. Eliminator plates 2 located downstream from the spray device 248 may be provided for removing particles of moisture from the air, these eliminator plates bein of any conventional construction. A valve 242 is provided for controlling the supply of moisture to the spray 248, there being a solenoid 243 or other suitable device for controlling the position of this valve. Upon deene'rglzation of the solenoid the valve 242 may be moved to closed position under the influence of gravity or any suitable biasing means (not shown).

The energization of the solenoid 243 is controled by a relay 258, this relay including opposed relay coils I, 252, an armature 253, operating arms 254 and 255 cooperating with fixed contacts 256 and 251, respectively. Power may be supplied to this relay through a suitable transformer 268. When the relay coil 25I is energized, the arms 254 and 255 are moved into engagement with their, respective contacts and upon deenergization of this relay coil the arms move out of engagement with their respective contacts under the influence of gravity or any suitable biasing means.

The energization of therelay coil 25I is conposition illustrated and the arm 269 is in engagement with neither contact 218 nor 21I. When the coil 266 is energized more highly than the coil 261, the arm 269 is moved into engagement with the contact 218 and when the coil 261 becomes more highlyenergized than the cell 266 the am 269 is moved into engagement with the contact 21I.

The energization of the relay 265 is controlled primarily byv a humidity responsive device. 215. This device may include a humidity responsive element 216 fixed at one end and being connected at its other end to a lever 211 pivoted at 218 and biased by means of a spring 219 in a direction to elongate the humidity responsive element 216. The element 215 may be located in the path of return air passing through the inlet 28 so that this device will respond to the average humidity existing in the various rooms or zones within the building. Upon an increase in humidity, the element 216 will become elongated whereupon the spring 219 will cause upward movement of the right end of lever 211 and upon a decrease in the humidity the contraction of the element 216 will cause opposite movement of the arm 211. The right end of this arm is arranged to move over a resistance 282, the upper end of this resistance being connected by means of conductors step-down transformer 298. The outer end of the coil 266 is connected by means of conductors 398 and MI to the opposite end of the secondary 291. The primary 299 of the transformer 298 is connected to the load side of a starting box 385 which controls the operationof the fan motor 24, this starting box being connected to the con-- ductors I68 and I6I by means of conductors 386 v and 381, respectively. When the motor 24 is in operation power will be supplied to the transformer 298 and accordingly to the relay 265 by means of the secondary 291.

It will now be seen that the relay coils 266 and 261 are connected in parallel with the potentiometer composed of the arm 211 and resistance 282. Movement of the arm 211 downwardly over the resistance 282 in response to a decrease in the relative humidity of the air passing over the element 216 will have the effect of decreasing the resistance in series with the relay coil 261 and increasing the resistance in series with the coil 266 whereupon the relay coil 261 becomes more highly energized than coil 266 and arm 269 is moved into engagement with the contact 21I. The engagement of arm 269 with the contact 21I will cause current to flow through therelay coil certain predetermined values.

III of the relay III as foilowsz' from the trans-'- former III, through conductors Il0,.Il I, contact Ill, arm III, conductors III, III, relay coil I5I. andconductor I back to the transformer I60. Energization-of the coil I5I causes movement of arias I54 and-I55 into engagement with the contacts III and I51. xUpon movement of arm I55 into engagement with contact I51 the solenoid I4I controlling the valve I4I of the spray is energized as follows: from one side of secondary I91 of the transformer I66, through conductors IN, I", arm I55, contact I51, conductor III, solenoid I4I and conductors III and I! to the other side of the secondary II1. Valve I4I is now opened and waterissues from. the spray 140 to increase the humidity of the air leaving the heating chamber I0. I

The engagement of arm 254 of the relay I60 with contact'I" closes a holding circuit through the relay coil I5l which is independent of the engagement of the arm I66 of relay I65 with the contact Ill, this circuitbeing as follows: from the side of the transformer I60 through conductor Ill-contact I56, arm I54, conductor III, relay coil III and conductor IN to the other side of-the transformer I60. Accordingly the coil'I5l of relay I50 will remain energized even though the humidity of the air passing over the controller Irises so that arm I11 moves upwardly to a point such that the relay coils I66 and I61 again become equally energized and the arm I66 moves out of engagement with contact Ill. ity,.the arm' I11 operated by the humidity re' sponsive element I16 will move upwardly until the resistance in series with the relay coil I61 becomeshigher than the resistance in series with relay coil III so that'the coil I66 becomes more highly energized than the coil I61 and armature III moves to the left moving switch arm I66 into engagement with the contact I10. flows through the relay coil III as follows: from the transformer III through conductors I I 0, contact I", switch arm I5 4, conductor III, switch arm III, contact I10, conductor-I25, the relay coil I5I and conductors I26 and 314 to the other side of the transformer I60. The energization of coil I5I counteracts the effect of coil I5I on the armature-I5I since the coil I5I has 'a bucking effect on coil Switch arms I54 and I55 now move out of engagement with the contacts I56 and I51 under the influence of gravity or other biasing means whereupon -the circuit through solenoid I4I of the water spray valve 242 is in tempted. Since the circuit through the relay coil I5I included the contacts I56 and 254, this circuitis interrupted when the arm I54 moves away from contact I56 and the relay coil 251 will not again be energized until the humidity of the air flowing over the element 216 drops to a low enough value so that the arm I66 of relay I65 is again moved into engagement with the contact Ill. It will thus be seen that the valve I4I is aa'saess Upon a furtherincrease. in relative humid- Current now operated in accordance with the humidity of the air passing through the return duct 26 to maintain the humidity of the air within that duct at The humidity at which the air is maintained may be varied in accordance with outdoor temperature so that when the temperatures fall low enough, frosting of the windows, etc., will not take place, For this purpose, a temperature, controller indicated generally by the reference character III is provided, this controller including bellows III connected by means of a capillary tube III ations in fresh air temperature.

to a bulb III located in the fresh air inlet I6, this tube, bulb, and bellows being provided with a suitable volatile fluid. The arm III of a bell cranklever is biased by means of a spring 336 into engagementwith the upper portion of the bellow III, the other arm IIl of this lever being arrange to sweep over a resistance I40 in response to vari-' As the temperature of the air entering the inlet 25 decreases the arm III will be moved toward the left by reason of the contraction of the bellows III. This resistance I40 is connected in parallel with the resistance III and the relay coils I66 and 261. The left end of this resistance, is connected by means of conductors I41 and I64 to the extremity of the relay coil I61 and the right end of this resistance is connected by means of conductors I42 and I61 to the left end of the coil I66. The arm In of controller I10 is connected by means of conductor 345, a variable resistance I46, conductor I41. and conductor I60 to the Junction of the coils I66 and I61. As the outdoor temperature decreases, the arm II1 moves to the left. The

resistance in series with the relay coil I66 decreases and this coil becomes more highly energized than the coil I61 whereupon-arm 269 is at-, tracted to the left, the engagement of this arm with contact I10 causing closing of the water valve 242 as explained above. It-is therefore apparent that upon a decrease in humidity of the airpassing over the element 215 the water valve 242 is opened to supply humidity to the air passing through the chamber I0 but as the temperature of the outdoor air decreases the water valve is moved to closed position. The provision of the adjustable resistance I46 in the circuit to the-arm II1 of the controller I has the effect of desensitizing this arm so that this arm must move throughout the entire range of the resistance I to have the same effect as movement of arm 211 of the controller I15 throughout the distance x. so that the controller IIO has the effect of shifting the'control range of the controller I15 to maintain different humidities of the air in-lthe various zones being conditioned in accordance with the outdoor temperatures. 'As the outdoor temperature drops, a lower humidity will be maintained in the various zones to prevent frosting of the window panes, etc. The provision "of the center tapped resistance over which thecontrol arm I11 of dampers l1 and II as will beseen in Figure 2.

The motors I50 include arms I5I driven thereby and connected by means of links III to the arms II to which the dampers l1 and II are connected. As the arm I5I moves upwardly dampers l1 are moved towards closed positionand dampers II are moved towards open position, Upon move ment of the arm I5I in the opposite direction a reverse movement of the dampers l1 and i8 takes Located in each of the zones 14 are thermostats I for controlling the operation of the motors 350. These thermostats may be of any suitable construction and are' illustrated as comprising a bimetallic element I61 to which is connected an arm 362' which is moved thereby in response to variations in temperature in the space being conditioned. Upon a rise in temperature within the space arm 362 is moved toward the right and upon a drop in temperature the arm 362 moves toward the left. The arm 362 is arranged to move over a resistance 365, the right end ofthis resistance being connected by means of conductors 366 and 361 to the motor te inal 310.- The opposite end of the resistance is connected by means of conductors 312 and=313 to the motor terminal 315.

The center terminal 316 of the motor is connected by means of conductors 318, 319, and the center tapped resistance 330 to the arm 362 of the thermostat 360. As the temperature within the space tiometers including resistances and control arms 402 mounted on a shaft 403 driven by a proportioning motor '404. The operation of the motor 404 is controlled by a temperature controller 405 including a bellows 406 connected by the capillary tube .401 to the bulb 408 located in the fresh air inlet 25. The bellows 406 controls the position of an arm 0 which is connected to a pivoted arm 4 biased by a spring 2 into engagement with the top of the bellows 406. The arm 0 sweeps over a resistance 5 having its ends connected by means of conductors M6 and 4| 1 to the outer terminals of the motor 404, the arm 0 being connected by means of conductor 8 to the center terminal of the motor 404. It will now be understood that as the fresh air temperature varies the motor 404 will be operated accordingly and will cause movement of the potentiometer arms 402 with respect to resistances 40L These resistances "I are connected in parallel with the resistances-365 of the thermostats 360 to the motors 350. Thus referring to Figure 2 it will be seen that the upper end of resistance IN is connected by means of conductors 420 and 31-3 to the terminal 315 of the motor 350. The lower end of resistance 4M is connected by means of conductors 422 and 361 to the terminal '310 and the arm 402 is connected by means of the adjustableresistance 425. conductors 426 and 310 to the terminal 316. The potentiometers 400 serve to adiust the control range X of the thermostat 360, these notentiometers having less eflect on the motor 350 than the thermostats by reason of the. adjustable resistances 425 inierposedin the c rcuits to the control arms 402. Since the arms 402 move in response to variations in outdoor temperature the tem eratures maintained in the zones or s aces M will depend upon the outdoor tem erature and the arrangement is such that as the outdoor temperature increases the temperature maintained in the zones will increase and conversely lower temperatures will be maintained in the zones as the outdoor temperature decreases during the cooling season. During the heating season, or in other words, when the outdoor temperature drops to a low enough value as termined schedule in order to secure the maximum conditions of comfort.

To review the operation of the system, the air admitted to the'air conditioning chamber will be kept at a substantially constant predetermined value as for example 58 F., when the outdoor temperature is not too high, by meansof the temperature controller 54 by regulating the settings of the fresh and return air dampers, and when the outdoor temperature rises above a certain value such as 75 the fresh air dampers 21 will be entirely closed whereby a minimum amount of fresh air only is admitted to the system. The temperature of the air leaving the cooling coils 40 to 43, inclusive, will be maintained at a predetermined value such as 58 by controlling the valves which admit cooling fluid to these coils by the controller I 2 I It will be understood that as long as the temperature of the air leaving the fan 23 is not above 58", the cooling coils will not be operating. The temperature of the air leaving the heating coils will be maintained at a value which will depend-upon outdoor temperatures by means of the controller I16 whose control range will be varied by the controller 205 responsive to fresh air temperatures. During the winter time the temperature of the air leaving the chamber 20 will be maintained between and E, for example, depending outdoor temperatures the higher the temperature of the airleaving the chamber 20. During the summer, when the temperature of the air leaving the fan is above 80 F., the heating coils will not be operating. The humidity of the air in the zones is controlled by the spray 240 which is in turn controlled by the humidity responsive device 215, the control range of this device being adjusted in accordance with outdoor temperatures so that as the outdoor temperature drops the control range of this humidity controller will vary to maintain a lower humidity in the spaces or zones being conditioned thereby preventing the formation of frost on window panes, etc. when the outdoor temperatures become very low. Thus. only during the seasons when the temperature oi the air leaving the fan 23 is between 58 F. and 80 F. will both the heatin and coolin means operate simultaneously. At all other times. only one of the means will be in operation at any time. and the temperature of the aces is controlled by controlling the amount of air being by-passed around the temperature chan in means in operation, the chamber housin the temperature changing means not in op-' ration serving as a by-pass for the other chamh r. In other words. when the outdoor tempe ature is low enough. there is no need to oberate the cooling means, the necessary cooling for any zone being effected by the mixture of this a r and the return air, and likewise, when the outdoor temperature is sufliciently high, there is no necessity for operating the heating means.

Since now the air leaving the chambers 20 and 2| is maintained at certain values the air being delivered to the various zones may be controlled by varying the proportions of the air admitted to the zones by adjustment of the dampers i1 and.

I8. Thus it may be desirable to maintain different temperatures in some zones than in others and the heating and cooling loads in the various zones may be so divergent that cooling may be required in one zone whereas heating may be required in another zone and this is readily efupon the outdoor temperatures, the lower the fected by properly controlling the dampers i1.

andilforeachzone.

It'will thus be seen that I have devised a very convenient and relatively simple air conditioning system whereby the condition, of the air in a number of-differentzones in a building is eifec--' tiveiy controlled even though one zonemay be requiring cooling while at the same time a different none is requiring heating. Having described a preferred form of my invention many of a volume of air at a substantially constant predetermined :value; means for' maintaining the temperature of a different volume of air at a different predetermined value, means for humidifying one of said volumes of air, means responsive the air leaving said heating means in controlof the heating means to prevent the temperature of sponsive to conditions in the space be ng ccndi tioned controlling the positions of said damper means, means responsive to thetemperature of the air leaving the heating means from dropping below a predetermined value, means responsive to the temperature of the air leaving the cooling means in control of the cooling means to maintain the air leaving the cooling means at-or be- J low a predetermined value, means for admitting to the humidity. at the air in said zones in control of the humidifying means, and means responsive to the' temperature of the air in each zonefor controlling the relative amounts of the two volumes of air admitted to each zone.

2. In an air conditioning system for a plurality of zones, means for maintaining the temperature of one volume of air at a substantially constant predetermined value, means for maintaining'the temperature of another volume of air at a pre- 3. In an air conditioning system, an air conditioning chamber, means dividing said chamber into parallelly arranged eways, heating means in one of said a 1eways, cooling means in other of said eways, circulating means for circulating air thro h saidchamber and through a space to be conditioned, means for admitting fresh and return air to said circulating means, means for controlling the proportions of fresh and return air to maintain the temperature of the air entering said chamber at a predetermined value as long as the fresh air temperature is suilciently .low, means for controlling the operation of the cooling means in a manner to maintain the temperature of the air leaving the coolin means at a value which is not lowerthan said first predetermined value, means for controlling the heating means in a manner to maintain the temperature of the heating means at a value which is higher than said last named value, and means responsive to the temperature of the s ace for controlling the relative amounts of air circulated through the two passageways.

4. In an air conditioning system, an air conditioning chamber. means dividing said chamber into parallelly arranged passageways, heating means in one of said passageways, cooling means in another of said means for cir-- culating air through the passageways and through a a controllable mixture of fresh and return air to ,said heating and cooling means, and means responsive. to the mixture of fresh and return air entering said chamber for controlling the relative amounts of fresh and return air admitted thereto in a manner to maintain the temperature of the mixture at substantially, the same-value as the temperature of the air leaving the'cooiing means is maintained, whenever powble, so that the cooling means is operated only when necessary in view of the high fresh air temperature and fluctuations of the load on the heatingmeans for circulating air through the passageways and through a space to be conditioned,- damper means in control of each of said passageways for regulating the relative amounts of 'air passing through each of said passageways into said space, means responsive to conditions in the space being conditloned controlling the positions of saiddamper means, means responsive to the temperature of the air leaving said'heating means ,in control of the heating means to prevent the-temperature of the air leaving the heating means from dropping below a predetermined value, means responsive to the temperature of the air leaving the' cooling means in control of the cooling means to maintain the air leaving the cooling means star below a predetermined value, means for admitting a controllable mixture .of fresh and return air to said heating and cooling means, means responsive to the mixture of fresh and return air entering said chamber for controlling the relative amounts of .fresh and return air admitted thereto in a manner to maintain the means ineffective and reducing to a minimum the admission of fresh air in response to a rise in outdoor temperature to a predetermined value.

6. In an air conditioning system. an air conditioning chamber, means dividing said chamber i to parallelly arranged passageways, heatin mea s in one of said passageways. cooling means in another of said passageways, means forcirculating air through the passageways and through a spaceto be conditioned, damper means incontrol of each of said passageways for regulating the. relative amounts of air passing through each of said passageways into said space, means responsive to conditions in the space being conditioned controlling a the positions of said damper means, means responsive to the temperature of the air leaving said heating means in control of the heating means to prevent the temperature of the. air leaving the heating means from dropping below a predetermined value, means responsive to the temperature of the air leaving the cooling means in control of the cooling meansto maintain the air leaving the cooling means at or below a predetermined value, means for admitting, a controllable mixture of fresh and return air to said heating and cooling means, means responsive to the mixture of fresh and return air entering said chamber for controlling the relative amounts of fresh and return air admitted thereto in a manner to maintain the temperature of the mixture at substantially the same value as the temperature of the air leaving the cooling means is maintained, whenever possible, so that the cooling means is operated only when necessary inview of the high fresh air temperature and fluctuations of the load on the heating means are minimized, and means responsive to outdoor tem perature for adjusting the temperature at which the air leaving the heating means is maintained.

'7. In a year round air conditioning system for ,a plurality of zones some of which may at times require heating while others simultaneously require cooling in order to maintain the desired conditions of temperature in the various zones, a common heating means for all of said zones, a common cooling means for all of said zones, means for causing a flow of air over the heating means and over the cooling means, means responsive to the temperature of the air leaving the heating means in control of the heating r temperature of the air leaving the cooling means below a predetermined value, duct means for delivering the air leaving the heating means and the cooling means to the various zones, and means responsive to the temperature of each zone for controlling the relative amounts of the air leaving the heating means and the coolin means admitted to the respective duct means whereby any desired temperature may be maintained in each of said zones at all times by the use of a common heating means and a common cooling means for all of said zones.

8. In a year round air conditioning system for a plurality of zones some of which may at times require heating while others simultaneously require cooling in order to maintain the desired conditions of temperature in the various zones, a common heating means for all of said zones, a common cooling means for all of said zones, means for admitting a mixture of return air from the various'zones and fresh outside air to the heating means and the cooling means, means for controlling said mixture in a manner to maintain the temperature of the air admitted to the heating and cooling means at or below a predetermined value whenever possible and reducing the amount of fresh air to a minimum whenever the outside temperature rises to such a value that it is not possible to maintain the mixed air temperature at or below this predetermined value, .means controlling the cooling means to maintain the temperature of the air leaving the cooling means at said predetermined value, operation of the cooling means being ten-- dered unnecessary when it is possible to maintain said predetermined value by controlling the mixture of fresh and return air, means controlling the heating means to maintain the temperature of the air leavingthe heating means at a predetermined value, and means responsive to the temperature of each zone for controlling the relative amounts of the air leaving the heating means and the cooling means admitted to the respective duct means whereby any desired temperature may be maintained in each of said zones at all times by the use of a common heating means and a commoncooling means for all of said zones.

9. In a year round air conditioning system for a plurality of zones some of which may at times require heating while others simultaneously requirecooling in order to maintain the desired conditions of temperature in the various zones, a common heating means for all of said zones, a common cooling means for all of said zones, means for causing a flow of air over the heating means and over the cooling means, a humidifying means in the path of. air flowing over the heating means, means responsive to the temperature of the air leaving the heating means in control of the heating means to main tain the temperature of the air leaving the heating means above a predetermined value, means responsive to the temperature of the air leaving the cooling means in control of the cooling means to maintain the temperature of the air leaving the cooling means below a predetermined value, duct means for delivering the air leaving the heating means and the cooling means to the various zones, means responsive to the humidity of the air leaving the zones in control of the humidifying means, and means responsive to the temperature of each zone for controlling the relative amounts of the air leaving the heating means and the cooling means admitted to the respective duct means whereby any desired temperature may be maintained in each of said zones at all times by the use of a common heating means and'a common cooling means for all of said zones.

10. A conditioning system comprising in combination, a zone, means for maintaining the temperature of a volume of air at a substantially constant predetermined value, means for maintainingthe temperature of a different volume of air at a different predetermined value. and means for controlling the temperature of the air in said zone by controlling the relative amounts of the said two volumes of air admitted to the zone.

11. A conditioning system comprising in combination, a zone, means for maintaining the temperature of a volume of air within a predeter mined temperature range and at a value within said range dependent uponbutdoor temperature, means for maintaining the temperature of a different volume of air at a substantially constant predeterminedvalue that is not within said predetermined temperature range, and means for controlling the temperature of the air in said zone by controlling the relative amounts of the said two volumes of air admitted to the zone.

GEORGE D. GULER. 

